Enteral nutrition is a form of hyperalimentation and metabolic support in which nutrient formulas or medicaments are delivered directly to the gastrointestinal tract. Fluid administration and aspiration is accomplished through use of a nasogastrointestinal tube generally referred to as an enteral feeding tube, as shown in FIG. 1. Enteral feeding is frequently utilized where adequate nutritional intake cannot be achieved through oral alimentation because of poor appetite, chronic nausea, general apathy, sedation or other symptoms or characteristics associated with serious disease. By delivering appropriate nutrient fluids directly to the gastrointestinal tract through an enteral feeding tube, nutritional and metabolic support of the patient is achieved without risk of sepsis or metabolic derangement, which may occur in intraveneous hyperalimentation. Because of increasing emphasis on out-patient care, enteral nutrition has been recognized as a desirable method of hyperalimentation as it requires only oral intubation of the feeding tube rather than manipulation of sterile cannulae or other means of interconnection with surgically implanted subclavian catheters as used in parenteral hyperalimentation.
Prior art feeding tubes, or catheters, typically include a rigid tip, or bolus, that includes a fluid outlet that promotes fluid flow. The fluid outlet is typically provided through a sidewall of the bolus to guard against occlusion with mucous, gastrointestinal debris or coagulated feeding material. The bolus is also more rigid than the enteral tube so that the tube can be easily guided during the intubation procedure. The enteral tube may also be provided with a wire stylet within the tube to provide more rigidity to the tube during intubation. The stylet can then be removed when the tube is inserted to the desired position within the gastrointestinal tract. Inadvertent exiting of the stylet during intubation is reduced by positioning the fluid outlet within the sidewall of the bolus.
In some situations, the enteral tube is introduced into the gastrointestinal tract in an over-the-wire intubation procedure. This procedure requires a bolus having an open ended tip. A wire stylet, or guide wire, extends through the enteral tube and out the open end of the bolus tip. The guide wire is used to guide the enteral tube and bolus to a location that may be more difficult to reach. The guide wire provides more control over the tube and bolus for placement in these locations. For example, the guide wire may be used to guide the bolus and enteral tube through the stomach and into the jejunum or duodenum. The guide wire, which is relatively stiff compared to the enteral tube, is inserted ahead of the bolus to a desired position. The enteral tube is then slipped over the wire and advanced to the desired position. When the enteral tube is properly placed, the wire is removed.
One disadvantage in the prior art is that an over-the-wire intubation procedure typically requires a bolus having a different design than those used in other procedures. Prior art boluses for use in an over-the-wire procedure are typically open-ended tubes that do not incorporate a rounded tip. On the other hand, boluses used in other types of intubation procedures typically have a rounded or bullet-shaped tip that provides less resistance during intubation. These shaped tips also reduce the risk of internal injury. Thus, each bolus design facilitates the specific intubation procedure.
Another disadvantage of prior art boluses is their susceptibility to bending and kinking at a collar portion of the bolus that connects to a distal end of the enteral tube. Since the enteral tube is made of a material that is typically more flexible than the bolus, kinking readily occurs at the joint between the materials of differing flexibility. These boluses are also susceptible to bending at the fluid opening, where there is less material to provide rigidity to the bolus. This bending and kinking makes controlled intubation more difficult. Furthermore, the bending and kinking of the collar portion may also cause problems when using a wire stylet. The overall lengths of the stylet and tube are subject to certain assembly tolerances. When the length of the stylet is within the shorter dimension range and the length of the tube is within the longer dimension range, the stylet may not reach the collar portion of the bolus. If the bolus is bent near the collar portion, the stylet may pierce the tube. On the other hand, if the length of the stylet is within the longer dimension range and the length of the tube is within the shorter dimension range, the stylet may be positioned within the fluid opening. In this situation, the stylet may pass through the fluid opening if the bolus is bent or kinked.
It is therefore an object of the present invention to provide a bolus for an enteral feeding tube that provides delivery of fluid to a body cavity or aspiration of a body cavity that does not become occluded with mucous, gastrointestinal debris and coagulated feeding material.
It is also an object of the present invention to provide a bolus for an enteral feeding tube that approximates the fluid flow rate characteristics of an open-ended tube.
It is also an object of the present invention to provide a bolus for an enteral feeding tube that has an elongated collar portion and a fluid outlet that is biased toward the distal end of the bolus to allow for greater tolerances between the lengths of the stylet and tube while preventing a shorter length stylet from piercing the tube or a longer length stylet from passing through the fluid outlet if the bolus is bent or kinked.
It is also an object of the present invention to provide a single bolus that can be used in more than one intubation procedure, including an over-the-wire procedure, by providing a stylet passage at the bolus tip while maintaining a generally contoured tip to promote travel through tortuous anatomy.
These and other objects of the present invention will become readily apparent after review of the specification and accompanying drawings.